In order to search databases and sources, you need to define your question as a series of individual concepts.

You will also need to consider listing synonyms to ensure you have thought of every way of referring to your concept.

An example proposal:

After the comprehensive study carried out by UK Vets Research in 2004, what evidence is there that domestic cats prefer meat to dry food?

 You should keep a complete list of these terms to apply to each of your chosen sources.

Limits

You should also consider which limits you want to place on your search. For example:

Dates - how far back do you want to go? Was there a change of policy, treatment or theory which mean you don't need to search before a certain date?

Publication type - are you only interested in articles, or clinical trials and RCTs, or do you want to include all materials?

Cohort - is your study just looking at men, or women, or a certain age group, or a particular style of painting or a certain geographical area?

Choosing limits will allow you to discard material which isn't relevant to your review.

For our example proposal we could apply the limits:

 - Publications after 2004

- Domestic cats only - no wild or 'big' cats, or zoo animals